pH-Dependent Assembly and Segregation of the Coiled-Coil Segments of Yeast Putative Cargo Receptors Emp46p and Emp47p

Emp46p and Emp47p are yeast putative cargo receptors that recycle between the endoplasmic reticulum and the Golgi apparatus. These receptors can form complexes in a pH-dependent manner, but their molecular mechanisms remain unclear. Here, we successfully reproduced their interactions in vitro solely with their coiled-coil segments, which form stable heterotetramers in the neutral condition but segregate at lower pH. Mutational data identified a key glutamate residue of Emp46p that serves as the pH-sensing switch of their oligomer formation. Our findings elucidate the mechanisms of the dynamic cargo receptor interactions in the secretory pathway and the design framework of the environment-responsive molecular assembly and disassembly systems.Emp46p与Emp47p是酵母的推定货物受体（cargo receptor），二者可在内质网（endoplasmic reticulum）与高尔基体（Golgi apparatus）之间循环。这类受体能够以pH依赖的方式形成复合物，但其具体分子机制仍不明确。本研究仅通过二者的卷曲螺旋（coiled-coil）结构域，便成功在体外重现了它们的相互作用；该结构域在中性环境下可形成稳定的异四聚体，而在低pH条件下则发生解离。突变数据鉴定出Emp46p上一个关键的谷氨酸残基，该残基充当了二者寡聚化过程的pH感应开关。本研究阐明了分泌通路中动态货物受体相互作用的分子机制，同时为环境响应型分子组装与解组装系统的设计提供了理论框架。